Facile preparation of porous sheet-sheet hierarchical nanostructure NiO/Ni-Co-Mn-Oxwith enhanced specific capacity and cycling stability for high performance supercapacitors

NiO, Ni-Co-Mn-O(x)and NiO/Ni-Co-Mn-O(x)on nickel foam substrates were preparedviaa chemical bath deposition-calcination. The thermodynamic behavior was observed by TG/DTA. The chemical structure and composition, phase structure and microstructures were tested by XPS, XRD, FE-SEM and TEM. The electrochemical performance was measured by CV, GCD and EIS. The mechanism for formation and enhancing electrochemical performance is also discussed. Firstly, the precursors such as NiOOH, CoOOH and MnOOH grow on nickel foam substrates from a homogeneous mixed solutionviachemical bath deposition. Thereafter, these precursors are calcined and decomposed into NiO, Co(3)O(4)and MnO(2)respectively under different temperatures in a muffle furnace. Notably, NiO/Ni-Co-Mn-O(x)on nickel foam substrates reveals a high specific capacity with 1023.50 C g(-1)at 1 A g(-1)and an excellent capacitance retention with 103.94% at 5 A g(-1)after 3000 cycles in 2 M KOH, its outstanding electrochemical performance and cycling stability are mainly attributed to a porous sheet-sheet hierarchical nanostructure and synergistic effects of pseudo-capacitive materials and excellent redox reversibility. Therefore, this research offers a facile synthesis route to transition metal oxides for high performance supercapacitors.